The OLED displays are recognized by the industry as the third-generation display technology after liquid crystal displays (LCDs), due to their numerous advantages such as light and thin, active luminescence, fast response, wide viewing angle, rich colors and high brightness, low power consumption, and high and low temperature resistance. The OLED displays are currently widely used in smart phones, tablet computers, televisions and other terminal products.
At present, in the manufacturing process of the OLEDs, evaporation procedure is implemented by a fine metal mask (FMM) to form a film on the substrate. As shown in FIG. 1, the FMM mainly includes a frame 2 and a mask plate 3. The mask plate is welded onto the frame. Generally, the mask plate is slightly longer than a length of a corresponding reserved portion on the frame, facilitating to weld the mask plate onto the frame. When the welding is completed, a redundant portion at the edge of the mask plate is removed. During the removing, the edge of the mask plate may be warped by a stress, which may adversely affect an attachment of the mask plate onto the substrate during the evaporation process, resulting in shadow effects near the edges of the formed pixel area. Further, during the welding, as shown in FIG. 1, solder joints 31 are formed, which will cause roughness in the surface of the mask plate.